The circulatory system is a very important system in which many living organisms, such as humans need. It consist of a network of vessels that deliver and circulate oxygen and nutrients throughout the whole body. Without a circulatory system, human would not able to survive because our cells would not receive enough oxygen or nutrients to perform tasks that help keeps us alive.
The circulatory system consists of: Blood
Blood vessels
Arteries: An elastic blood vessel carries blood away from heart to all the parts of your body. There are to type of arteries: pulmonary artery and systemic artery. Pulmonary artery is a blood vessel that carry blood from your heart to your lung where the blood pick up oxygen. Systemic artery delivers blood to the rest of your body.
Arterioles: Very small arteries that branch out from the artery lead to the capillary. The arterioles have almost all the same features with the arteries
Capillaries: Small blood vessels that connect the vein and the arteries. The capillaries can be found within the tissue of the body, this blood vessels are so small that blood cells can only travels though them in single file. The size of capillaries are about 5 -10 micron in diameter
Veins: elastic blood vessels that carries blood to heart. Vein can range in size from 1 - 1.5 cm in diameter
Venules: Smallest veins in the body, the venules branched out and carry blood to the largest vein in the body, the vene cava which later carry the blood to the right atrium of the heart.
Heart (it is a muscular organ and it is what keeps the transport system moving)
(it would be a good idea to visit "The Heart" page in order to understand more about the circulatory system as the heart is an important part)
The Transport System There are four parts to the transport system which are; the medium, system of tubes, a pump and site of exchange
Component
Part
Role/ function
Medium
Blood
The fluids that flow in the system and carries materials around our body, blood is made up or red blood cells.
Tubes
Arteries and Vein
The system of tubes that carry our blood from place to place
Pump
Heart
A pump that supplies pressure to keep the fluid moving through the tube
Site of exchange
Capillaries
Allows diffusion with cells
The BloodAs it have mentioned above, blood is the fluid that flows in the system and has different parts to it which are:
Main Function
Structures
Plasma
Carries blood cells and other components throughout the body
It is the liquid of the blood
Red blood cells (Erythrocytes)
Transports oxygen and carbon dioxide between lungs and tissues
The surface is covered with iron containing pigment hemoglobin, which picks up and lets go of oxygen
Has no nucleus, and leaves more space for hemoglobin
Small and flexible so it fits through capillaries more easily
White blood cells (Lymphocytes)
Produces antibodies that help in the defense against diseases
Has large nucleus which contain many copies of genes to make many antibodies
White blood cells(Phogocytes)
Engulfs invading micro organisms
Flexible so can grow around invaders
Cytoplasm has enzymes to digest microorganisms
Has sensitive cell surface membrane to detect microoragnisms
Platelets
Cell fragments involved in blood clotting
Is able to release blood clotting enzymes
How the blood flows through the blood vessels
As the blood flows through our system it goes through these vessels: (from http://www1.bellevuepublicschools.org/curriculum/k6web/fifthgrade/bodysys/arteries2.jpg) The blood leaves the left side of the heart through the arteries to the capillaries. To be more specific, in between this stage there are the arterioles which transport the blood from the arteries to the capillaries. Once it is at the capillaries the food and oxygen is released to the body cells. Then carbon dioxide as well as other wastes is returned to the blood stream. Next the blood travels in the veins back to the right side of the heart. Again, in between, there are the the venules which drain the blood from the capillaries into the veins.
The table below will show and explain the main function and structure of these vessels:
Diagram
Function
Arteries (the main artery is called aorta)
Carries blood away from the heart
The elastic walls expand and relax as the blood is forced out of the heart.
Thick walls withstand the high pressure of blood.
Rings of the muscle can narrow or widen the artery and control the blood flow in it according to the needs.
Arterioles
Transports blood from arteries to capillaries
Have tiny braches that lead to capillaries
It is under the contol of sympathetic nervous system in order to regulate blood flow
Capillaries
Connect arteries to veins.
Nutrients, oxygen and wastes pass in and out of through the capillary walls.
Walls are only one cell thick (so that substances do not have far to dissolve)
High branched to cover enormous surface area (more space for diffusion)
Constantly supplied with fresh blood sothatgradients diffusion can occur.
Veins (the main vein is called vena cava)
Carries blood to the heart
Have valves that prevent the backflow of blood.
Nearby muscles squeeze the veins and help push blood back towards the heart
Large diameter and thin walls reduce resistance to the flow of blood.
Venules
Drains blood from capillaries into veins
They are minute vessels
Many venules unite and form a vein
Here is a video animating the concept of blood circulation in the human body:
Above is a diagram of the two circuits in a double circulatory system. The first circuit is the Systematic circuit, the main circuit. It carries oxygenated blood around the body in the arteries, and deoxygenated blood back to the heart along the veins. The second circuit is called the pulmonary circuit which includes the heart and lungs. It carries deoxygenated blood from the heart to the lungs to be oxygenated. Shown on the diagram above, the systematic circuit leaves from the left side while the pulmonary leaves from the right side of the heart.
Shown below is a more complex diagram of the double circuit circulatory system. Basically, here, the right side of the heart collects the oxygen-rich blood that is returning from the lungs, through the pulmonary veins. The oxygen-rich blood is then delivered to other parts of the body and they become oxygen-poor blood. Once that has occurred, the oxygen-poor blood is returned to the left side of the heart, through the inferior vena cava and the superior vena cava. Once in the left side of the heart, the oxygen-poor blood is delivered to the lungs, through the pulmonary artery to be oxygenated so that the cycle can start again.
The circulatory system is a very important system in which many living organisms, such as humans need. It consist of a network of vessels that deliver and circulate oxygen and nutrients throughout the whole body. Without a circulatory system, human would not able to survive because our cells would not receive enough oxygen or nutrients to perform tasks that help keeps us alive.
The circulatory system consists of: Blood
- Blood vessels
- Arteries: An elastic blood vessel carries blood away from heart to all the parts of your body. There are to type of arteries: pulmonary artery and systemic artery. Pulmonary artery is a blood vessel that carry blood from your heart to your lung where the blood pick up oxygen. Systemic artery delivers blood to the rest of your body.
- Arterioles: Very small arteries that branch out from the artery lead to the capillary. The arterioles have almost all the same features with the arteries
- Capillaries: Small blood vessels that connect the vein and the arteries. The capillaries can be found within the tissue of the body, this blood vessels are so small that blood cells can only travels though them in single file. The size of capillaries are about 5 -10 micron in diameter
- Veins: elastic blood vessels that carries blood to heart. Vein can range in size from 1 - 1.5 cm in diameter
- Venules: Smallest veins in the body, the venules branched out and carry blood to the largest vein in the body, the vene cava which later carry the blood to the right atrium of the heart.
- Heart (it is a muscular organ and it is what keeps the transport system moving)
(it would be a good idea to visit "The Heart" page in order to understand more about the circulatory system as the heart is an important part)Diagram of Circulatory System
http://www.daviddarling.info/encyclopedia/C/circulatory_system.html
The Transport System
There are four parts to the transport system which are; the medium, system of tubes, a pump and site of exchange
The BloodAs it have mentioned above, blood is the fluid that flows in the system and has different parts to it which are:
How the blood flows through the blood vessels
As the blood flows through our system it goes through these vessels:
(from http://www1.bellevuepublicschools.org/curriculum/k6web/fifthgrade/bodysys/arteries2.jpg)
The blood leaves the left side of the heart through the arteries to the capillaries. To be more specific, in between this stage there are the arterioles which transport the blood from the arteries to the capillaries. Once it is at the capillaries the food and oxygen is released to the body cells. Then carbon dioxide as well as other wastes is returned to the blood stream. Next the blood travels in the veins back to the right side of the heart. Again, in between, there are the the venules which drain the blood from the capillaries into the veins.
The table below will show and explain the main function and structure of these vessels:
(the main artery is called aorta)
- Transports blood from arteries to capillaries
- Have tiny braches that lead to capillaries
- It is under the contol of sympathetic nervous system in order to regulate blood flow
(the main vein is called vena cava)
Here is a video animating the concept of blood circulation in the human body:
(from http://www.youtube.com/watch?v=PgI80Ue-AMo&feature=related)
Double Circulation
Double blood circulation is when the blood passes through the heart twice for each complete circuit of the body.
(from http://leavingbio.net/CIRCULATORY%20SYSTEM/CIRCULATORY%20SYSTEM_files/image034.jpg)
Above is a diagram of the two circuits in a double circulatory system. The first circuit is the Systematic circuit, the main circuit. It carries oxygenated blood around the body in the arteries, and deoxygenated blood back to the heart along the veins. The second circuit is called the pulmonary circuit which includes the heart and lungs. It carries deoxygenated blood from the heart to the lungs to be oxygenated. Shown on the diagram above, the systematic circuit leaves from the left side while the pulmonary leaves from the right side of the heart.
Shown below is a more complex diagram of the double circuit circulatory system. Basically, here, the right side of the heart collects the oxygen-rich blood that is returning from the lungs, through the pulmonary veins. The oxygen-rich blood is then delivered to other parts of the body and they become oxygen-poor blood. Once that has occurred, the oxygen-poor blood is returned to the left side of the heart, through the inferior vena cava and the superior vena cava. Once in the left side of the heart, the oxygen-poor blood is delivered to the lungs, through the pulmonary artery to be oxygenated so that the cycle can start again.
The advantage of the double circulatory system is that oxygen from the lungs can be picked up and transported to the body tissues much quicker.
(from http://leavingbio.net/CIRCULATORY%20SYSTEM/CIRCULATORY%20SYSTEM_files/image036.jpg)
The image above is a more detailed and complex diagram of the double circulation.
http://www.youtube.com/watch?v=PgI80Ue-AMo
WORK CITED
"The Circulatory System." Global Classroom . N.p., n.d. Web. 31 May 2011. http://www.globalclassroom.org/hemo.html.
"Circulatory System." The Worlds of David Darling. Web. 01 June 2011. http://www.daviddarling.info/encyclopedia/C/circulatory_system.html.
"Systemic and Pulmonary Circulation." YouTube - Broadcast Yourself. Web. 31 May 2011. http://www.youtube.com/watch?v=0jznS5psypI.